I'm not really the main photog for this, just accompanied a friend and was just a spectator for the day but can't resist trying out his Tamron 70-200

I know a lot of things are wrong in this shot especially the lighting for the runway shoot, but we cannot deny that the Tamron even with the D40 is sharp and the AF is spot on.

At ISO 400 1/160 F2.8, the lighinting is not bad at all. and the subject is either static or moving rather slowly at a fairly far distance, it is in no way a real test of this lens's AF speed and accuracy.